Inexsufflator

ABSTRACT

A manual inexsufflator including a standard mechanical ventilator, a medical suction unit, and a piston-like sliding valve mechanism which connects a patient ventilation interface with either the ventilator or the suction unit. By sliding the valve mechanism in and out the user selectively connects the patient to either the ventilator, for purposes of insufflation, or the suction unit, for purposes of exsufflation. The ventilator may generate expiratory positive airway pressure between inexsufflation cycles.

CROSS-REFERENCE TO PREVIOUS APPLICATIONS

This application is a continuation-in-part application of and claimspriority from U.S. Patent 09/975,943, filed Oct. 15, 2001.

FIELD OF THE INVENTION

The present invention relates generally to respiratory apparatus, andparticularly to an inexsufflator useful, for example, in clearingrespiratory secretions from airways.

BACKGROUND OF THE INVENTION

Patients suffering from weakness of the muscles of the thoracic cage anddiaphragm, as may occur in, for example, Duchenne Muscular Dystrophy orCervical Spine Injury, are often unable to cough effectively, if at all.Due to their inability to clear respiratory secretions from their lowerrespiratory tract, retained secretions may develop in their lungs. Asretained secretions constitute a focus for infection, these patients areat high risk of developing severe, and potentially fatal, pneumonia, andare thus in need of assistance in expectorating their respiratorysecretions.

Several techniques for assisting such patients are known. If the degreeof muscle weakness is mild, physical therapy techniques such as“manually assisted coughing” may be effective. With this technique, thetherapist enhances the efficacy of the patient's natural cough by meansof a hand thrust on the patient's ribcage or abdomen, timed incoordination with the patient's natural coughing action. If the degreeof muscle weakness is severe, however, the patient will requiremechanical assistance to achieve adequate pulmonary toilet.

For patients who are intubated with an endotracheal tube, or have apermanent tracheostomy cannula in place (either of which may benecessary for purposes of mechanical ventilation due to the severity ofthe chest wall muscle weakness), endotracheal suction is commonly usedas a technique for secretion clearance. Endotracheal suction is achievedby inserting a narrow gauge catheter into the patient's trachea via alarger gauge endotracheal tube or tracheostomy cannula, and thenapplying suction through the catheter. Secretions that are in proximityto the tip of the catheter are then sucked into the catheter andremoved. This technique achieves secretion removal by utilizing asuction force to cause secretions to either adhere to the catheter tipor enter into the catheter, which is then withdrawn from the body whilethe suction force is maintained. It should be noted that the suction isgenerated within the suction catheter only, not within the endotrachealtube or tracheostomy cannula, and that it is executed at any stageduring the patient's respiratory cycle, be it inspiration or expiration.

There are several drawbacks to endotracheal suction as a means forclearing respiratory secretions. The procedure is invasive, thusrequiring sterile technique for its performance, and may cause physicaltrauma to, or infection within, the patient's airways. Moreover, thistechnique can only be performed on those patients who are alreadyintubated or tracheostomized, and is not relevant to the majority ofpatients who do not have instrumentation within their respiratory tract.

For non-intubated patients, and for intubated patients who wish to avoidthe above-mentioned drawbacks of endotracheal suction, a desirablemechanical method for removal of tracheobronchial secretions is that ofmechanical insufflation-exsufflation (also known as inexsufflation), bymeans of an inexsufflator. The Concise Oxford Dictionary, SeventhEdition, Oxford University Press, 1985, defines insufflation as “blowingair into a cavity of the body”, and Blackiston's Gould MedicalDictionary, Fourth Edition, McGraw-Hill, 1979, defines exsufflation as“forcible expiration; forcible expulsion of air from lungs by amechanical apparatus”.

Most commonly, an inexsufflator is applied to a patient's respiratorytract via a facemask held hermetically over the patient's mouth andnose, a nasal mask, nasal prongs, or a mouthpiece held in the patient'smouth. All of the aforementioned are hereinafter referred to as“noninvasive ventilation interfaces”, by which is meant a ventilationinterface that does not penetrate into the patient's trachea, but ratherinterfaces with the patient's mouth and/or nose. Alternatively, if thepatient is intubated or has a tracheostomy, the inexsufflator may beattached directly to the endotracheal tube or tracheostomy cannula(which are “invasive ventilation interfaces”). Typically, aninexsufflator functions in a cyclical fashion as follows: First, theinexsufflator mechanically pumps air into the patient's lungs until thelungs have expanded to their maximum capacity (insufflation). Then, atthe moment of peak insufflation, the inexsufflator rapidly sucks air outof the patient's lungs at a high flow rate. This rapid flow of airthrough the patient's respiratory tract outward (exsufflation) carrieswith it secretions from the lower respiratory tract. In this manner, aninexsufflator artificially simulates the action of a natural cough.

Thus, in contrast to endotracheal suction, inexsufflation is noninvasive(and thus does not require sterile technique or cause trauma to theairways), and achieves secretion removal by causing rapid airflow (atleast 160 liters/minute) through the entire respiratory tree, as occursduring a physiological cough. This airflow “blows” the secretions up thetrachea and into the patient's mouth (or tracheostomycannula/endotracheal tube if the patient is intubated).

Many patients in need of an inexsufflator have weakness of their facialand glossopharyngeal muscles in addition to the weakness of their chestwall muscles, and they typically are unable to “hold in” a deep breathfor a significant period of time. As such, after an inexsufflatorcompletes the lung insufflation cycle, the insufflated air may rapidlydissipate through the patient's. mouth and nose. It is thus of criticalimportance for the successful functioning of an inexsufflator that thecycle of mechanical exsufflation commences immediately after fullinsufflation has been achieved, prior to air dissipation, because if theonset of exsufflation is even marginally delayed the volume of airwithin the patient's lungs which will be available for mechanicalexsufflation will be significantly diminished, resulting in anineffective “cough”.

Mechanical inexsufflation is particularly effective when it is augmentedby the manual assisted cough technique described above. This is usuallydone by a single caregiver (often a physiotherapist or a member of thepatient's family) who operates the inexsufflator while simultaneouslyapplying abdominal/chest thrusts timed to the exsufflation phase of themachine.

It is physiologically desirable that each insufflation-exsufflationcycle be separated from the preceding or following cycle by a pause ofat least a few seconds, so as to prevent hyperventilation of thepatient. During this expiratory pause period no airflow is generated bythe inexsufflator, such that the intrapulmonary pressure equilibrates toatmospheric pressure (that is, zero) during this time, until the onsetof the next insufflation.

Standard inexsufflators, such as the CoughAssist Inexsufflator (J. H.Emerson Co. Cambridge, Mass.) utilize a blower to generate airflowwithin the machine. This mechanism is used to generate airflowalternately in two directions: into the lungs under positive pressureduring insufflation, and out of the lungs under negative pressure duringexsufflation. In the “automatic” version of this machine, model CA-3000,cycling from insulation to exsufflation is achieved by means of anelectrically operated switching mechanism that automatically redirectsthe direction of airflow between the patient and the machine (eitherinto or out of the blower) according to a predefined time sequence.Alternatively, the operator can control the timing of theinsufflation-exsufflation cycles by pushing an electric switch in arespectively rightward or leftward direction while the machine isoperating, in accordance with the time sequence desired by the operator.

The electrical timing mechanism within automatic inexsufflators, and themechanism for generating positive-pressure airflow into the patient,makes these devices both electronically complex and expensive. The costof such devices (approximately $5000 in 2002) is of particularimportance because many patients in need of an inexsufflator areconcurrently in need of a similarly expensive mechanical ventilator forpurposes of mechanical ventilation via an invasive or noninvasiveventilation interface, as their chest wall muscle weakness limits notonly their ability to cough, but also their ability to breath adequatelyand independently. Such patients, who are often already using amechanical ventilator, are thus compelled to acquire an additionalexpensive ventilatory device if they wish to perform mechanicalinexsufflation.

So as to decrease the cost of standard inexsufflator devices, “manual”versions of the CoughAssist Inexsufflator have been developed, such asthe CoughAssist model CM-3000 (J. H. Emerson Co. Cambridge, Mass.),which does not have an electrical timing mechanism. In this manualversion, the operator manually controls the timing of theinsufflation-exsufflation cycles by swiveling or rotating a mechanicalnon-electronic handle to-and-fro in a respectively rightward or leftwarddirection, so as to mechanically redirect the direction of patientairflow into or out of the blower.

Standard inexsufflators, however, are known to suffer from severaldeficiencies:

1) The equilibration of intrapulmonary pressure with atmosphericpressure that occurs during the expiratory pause phase of therespiratory cycle impedes effective secretion clearance. This is becausethe lack of positive (i.e. supra-atmospheric) intrapulmonary pressureduring this period encourages the collapse of smaller airways andalveoli, which traps secretions deep within the lung.

2) Standard inexsufflators are comprised of a built-in mechanism forgenerating airflow in two directions (both into and out-of the patient'slungs), which is mechanically complex. As such, standard inexsufflators(both manual and automatic versions) are expensive, with even manualinexsufflators costing approximately $3000 in 2002.

3) It is difficult for a caregiver performing the manual assisted coughtechnique simultaneously with mechanical inexsufflation to achieveoptimal coordination with a manual inexsufflator. This is because eachof the caregiver's hands have to perform a different maneuversimultaneously: while one hand has to perform an “in-out”abdominal/chest thrust on the patient, the other hand has to perform a“side-to-side” rotary movement of the swivel handle on the manualinexsufflator. Precise coordination of left and right hand movements,which is essential for achievement of effective cough flows, isparticularly difficult when each hand is performing a different grossmotor movement.

SUMMARY OF THE INVENTION

The present invention seeks to provide a manual inexsufflator that issimple and inexpensive, yet efficient and effective in artificiallyreproducing a coughing action to clear respiratory secretions from lungsand airways.

In general terms, the inexsufflator of the current invention maycomprise three primary components: 1) a mechanical ventilator, 2) asuction unit, and 3) a sliding, piston-like, valve mechanism, whichconnects the above two components to a patient ventilation interface(such as a noninvasive or an invasive ventilation interface).

Each of the three primary components may be easily attached to anddetached from each other by means of standard ventilator tubing. Anytype of standard mechanical ventilator, including ventilators of thetype used by patients with chest wall weakness for purposes ofmechanical ventilation, may be used as part of the inexsufflator of thecurrent invention. The same ventilator may concomitantly be used by thepatient for regular mechanical ventilation between inexsufflationsessions. Consequently, for the many patients who already possessstandard ventilators, only the piston-valve and suction components ofthe current invention need be added so as to “convert” their ventilatorsinto inexsufflators, in terms of the current invention. As such, for apatient who already owns a ventilator, acquiring the current inventionentails substantially less expense than that entailed in acquiring anindependent, standard inexsufflator.

In one embodiment of the current invention, the mechanical ventilator isof a type that is capable of actively generating and maintainingpositive end-expiratory pressure (PEEP), also known as expiratorypositive airway pressure, during the pause between inexsufflationcycles.

The piston-valve establishes airflow continuity between the patientinterface and, depending on the valve's orientation (i.e., piston“pushed in” or piston “pulled out”), either the ventilator or thesuction unit, both of which operate continuously. The operator of theinexsufflator causes the device to cycle between insufflation andexsufflation by manually pulling the piston of the valve outward (whenthe ventilator is delivering a breath) and then pushing it inward (atthe moment that mechanical inhalation terminates). In so doing, theoperator selectively and exclusively establishes airflow continuitybetween the patient and either the mechanical ventilator (thus achievinginsufflation) or the suction unit (thus achieving exsufflation) in analternating manner respectively. Between inexsufflation cycles thepiston is pulled outwards, so that the ventilator delivers PEEP to thepatient until the onset of the next mechanical breath. As such,intra-alveolar pressure does not remain at zero after exsufflation hasterminated, thus preventing alveolar or airway collapse

The “in-out” movement of the piston-valve parallels the arm action of anabdominal/chest thrust as is done for purposes of assisted coughing.Thus, an operator performing an abdominal thrust with one hand whileinitiating a mechanical exsufflation with the other hand performs thesame gross motor movement with each hand simultaneously. This uniformityof hand movement facilitates exact coordination of the two actions bythe operator, thus enhancing the efficacy of the procedure.

In an embodiment of the invention, an external mechanical ventilator maybe used for generating insufflation in the current invention, ratherthan a dedicated, “built-in” source of positive pressure airflow. Anexpiratory positive airway pressure may be generated during the pausebetween insufflation-exsufflation cycles, by means of the mechanicalventilator.

The manual valve mechanism may be operated by an “in-out” or “push-pull”type of hand/arm movement, rather than a “side-to-side” rotary movement.

There is thus provided in accordance with a preferred embodiment of thepresent invention an inexsufflator including a patient interface unit, asource of negative fluid pressure, a source of positive fluid pressure,wherein the source of positive fluid pressure includes at least one of amechanical ventilator operative to generate an expiratory positiveairway pressure and a volume-cycled mechanical ventilator, and a valveconnected to the source of positive fluid pressure and the source ofnegative fluid pressure, the valve being adapted to selectively connectthe patient interface unit with the source of positive fluid pressureand the source of negative fluid pressure.

Further in accordance with a preferred embodiment of the presentinvention the valve includes a manual valve.

In accordance with a preferred embodiment of the present invention themanual valve includes a sliding element.

There is also provided in accordance with a preferred embodiment of thepresent invention an inexsufflator including a patient interface unit, asource of negative fluid pressure, a source of positive fluid pressure,and a manual valve connected to the source of positive fluid pressureand the source of negative fluid pressure, the valve being adapted toselectively connect the patient interface unit with the source ofpositive fluid pressure and the source of negative fluid pressure, andthe valve including a sliding element.

In accordance with a preferred embodiment of the present invention thepatient interface unit includes a noninvasive ventilation interface.

In accordance with a preferred embodiment of the present invention themanual valve is adapted to substantially seal fluid flow from the sourceof positive fluid pressure to the patient interface unit while generallysimultaneously opening fluid flow from the source of negative fluidpressure to the patient interface unit.

Further in accordance with a preferred embodiment of the presentinvention the inexsufflator includes a working cycle that includesproviding positive fluid pressure from the source of positive fluidpressure via the valve to the patient interface unit, and, within apredetermined period of time, substantially sealing fluid flow from thesource of positive fluid pressure to the patient interface unit whilegenerally simultaneously providing negative fluid pressure from thesource of negative fluid pressure via the valve to the patient interfaceunit.

Still further in accordance with a preferred embodiment of the presentinvention at least one pressure sensor is adapted to sense at least oneof the positive fluid pressure and the negative fluid pressure.

Further in accordance with a preferred embodiment of the presentinvention the sliding element includes a first orientation and a secondorientation, wherein in the first orientation the sliding elementpermits fluid flow from the source of positive fluid pressure to thepatient interface unit, but substantially seals fluid flow from thesource of negative fluid pressure to the patient interface unit, and inthe second orientation the sliding element substantially seals fluidflow from the source of positive fluid pressure to the patient interfaceunit but permits fluid flow from the source of negative fluid pressureto the patient interface unit.

Still further in accordance with a preferred embodiment of the presentinvention the sliding element includes a piston that slides in a housingbetween the first and second orientations.

In accordance with a preferred embodiment of the present invention thepiston has an aperture formed therein adapted to be selectively in fluidcommunication with an opening formed in the housing.

Further in accordance with a preferred embodiment of the presentinvention the sliding element includes a sealing element that is inselectively sealed engagement with the piston.

Further in accordance with a preferred embodiment of the presentinvention the source of negative fluid pressure includes a medicalsuction unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with theappended drawings in which:

FIG. 1 is a simplified pictorial, exploded illustration of aninexsufflator constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 2 is a simplified pictorial illustration of the inexsufflator ofFIG. 1 in a first orientation comprising insufflation of a patient, inaccordance with a preferred embodiment of the present invention; and

FIG. 3 is a simplified pictorial illustration of the inexsufflator ofFIG. 1 in a second orientation comprising exsufflation of the patient,in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Reference is now made to FIGS. 1 and 2, which illustrate aninexsufflator 10 constructed and operative in accordance with apreferred embodiment of the present invention.

Inexsufflator 10 preferably includes a patient interface unit 12 (FIG.2), which may comprise, without limitation, an invasive ventilationinterface (for example, a tube connector that connects directly to atracheostomy cannula, not shown) or a noninvasive ventilation interface(for example, a facemask applied to a patient's face). A source 14 ofnegative fluid pressure may be provided, such as but not limited to, astandard medical suction unit, for example, an Accuvac Basic Aspirator(Gottlieb Weinmann GmbH & Co. Hamburg, Germany) a vacuum cleaner or anyother suitable suction device. A source 16 of positive fluid pressuremay be provided, such as but not limited to, a mechanical ventilator oran “AMBU” type manual resuscitator bag, for example. It is noted thatthe sources 14 and 16 of negative and positive fluid pressure,respectively, may be manually or automatically controllable with anysuitable control apparatus, sensors, recording devices and the like (notshown).

A manual valve 18 is preferably connected to the source 14 of negativefluid pressure and to the source 16 of positive fluid pressure. Valve 18is adapted to selectively connect patient interface unit 12 with sources14 or 16 of negative and positive fluid pressure, respectively.

The following is one example of a construction of manual valve 18,although it is understood that the manual valve 18 is not limited tothis construction. In the illustrated embodiment, manual valve 18comprises a cylindrical housing 20 having a connector element 22 forconnection to patient interface unit 12 and another connector element 24for connection to the source 14 of negative fluid pressure. An aperturecontrol device 26 may be provided at the interface between housing 20and connector element 24 for varying the amount of negative pressure,i.e., controlling the amount of suction. Housing 20 may have an opening27 that fluidly communicates with connector element 24. One or morepressure sensors 28 may be provided for sensing the positive fluidpressure or the negative fluid pressure, such as but not limited to, aPitot tube or a manometer on housing 20 (pressure sensor 28 is omittedfor clarity in FIGS. 2 and 3).

Manual valve 18 may comprise a sliding element 30 that may include ahollow cylindrical piston 32 that slides in housing 20. Piston 32 mayhave an aperture 34 formed therein adapted to be selectively in fluidcommunication with opening 27 of housing 20, as described more in detailhereinbelow. A sealing element 36 may be provided that is in selectivelysealed engagement with piston 32 of sliding element 30. Sealing element36 may comprise a hollow cylinder with a tapered end 38. Tapered end 38may be formed with a plurality of openings 40 through which a fluid,such as air, may pass. A seal 42, such as an O-ring, may be placed attapered end 38 proximal (i.e., closer to the connector element 22) toopenings 40. Sealing element 36 may be coupled to piston 32, withoutlimitation, by means of a tongue 44 that protrudes from a proximal endof sealing element 36 and which is received in aperture 34. A screw 48may optionally protrude into a groove 46 on the outer surface of piston32 and serve as a stop to limit the travel of piston 32 in housing 20.

Sliding element 30 comprises a first orientation and a secondorientation. In the first orientation, shown in FIG. 2, sealing element36 does not abut against piston 32 and fluid may flow from the source 16of positive fluid pressure to patient interface unit 12. However,aperture 34 is not aligned with opening 27 of housing 20 and thussliding element 30 substantially seals fluid flow from the source 14 ofnegative fluid pressure to patient interface unit 12.

In the second orientation, shown in FIG. 3, sliding element 30 has beenmoved generally in the direction of an arrow 50 (towards the connectorelement 22 that connects to patient interface unit 12). In the secondorientation, seal 42 of sealing element 36 abuts against piston 32 andsubstantially seals fluid flow from the source 16 of positive fluidpressure to patient interface unit 12. Tongue 44 is adapted to pullpiston 32 when piston 32 is manually moved out of housing 20 by anoperator of inexsufflator 10, and seal 42 is adapted to push piston 32when piston 32 is moved into housing 20 by the operator of inexsufflator10. Aperture 34 is now aligned with opening 27 of housing 20 and thussliding element 30 permits fluid flow from the source 14 of negativefluid pressure to patient interface unit 12. Thus, manual valve 18 mayoperate like a two-way valve.

A working cycle of inexsufflator 10 for providing air to a patient andsuddenly causing the patient to cough is now described with reference toFIGS. 2 and 3. In FIG. 2, source 16 of positive fluid pressure suppliespositive fluid pressure via manual valve 18 to patient interface unit12, which pressure is forced into the airways and respiratory system ofthe patient. The positive pressure may be monitored by observingpressure sensor 28. In particular, the user monitors pressure sensor 28so as to discern the onset and peak of insufflation. At or near themoment of maximal lung insufflation, as depicted by an increase in thepressure recorded on pressure sensor 28 or as discerned by observationof the patient's chest wall movement, the user initiates exsufflation asfollows: Within a predetermined period of time, preferably rapidly andsuddenly so as to prevent air dissipation prior to the onset ofexsufflation, the user moves manual valve 18 to the second orientationshown in FIG. 3. For example, the user may suddenly and quickly slidesliding element 30 in the direction of arrow 50, thereby substantiallysealing fluid flow from the source 16 of positive fluid pressure topatient interface unit 12, while generally simultaneously providingnegative fluid pressure from the source 14 of negative fluid pressurevia manual valve 18 to patient interface unit 12. The sudden applicationof negative pressure to the lungs that have been insufflated with thepositive pressure may generate a rapid airflow out of the lungs of thepatient, thereby achieving exsufflation. During the process ofexsufflation, the user monitors pressure sensor 28 so as to discern thedegree of negative pressure being generated within the patient'sairways. After a predetermined period of time, such as but not limitedto about 1 second, or upon attainment of a desired degree of negativepressure within the airways, the manual valve may be returned to thefirst orientation so as to terminate the phase of exsufflation and startthe working cycle again.

In a first embodiment of the current invention, source 16 of positivefluid pressure is a hand-held “AMBU” type manual resuscitator bag, forexample, an MR-100 Adult Resuscitator (Galemed Corp. Taiwan). In termsof this embodiment, the phase of insufflation is initiated by the usermanually squeezing the manual resuscitator bag so as to generatepositive pressure within the patient's airways, as depicted by pressuresensor 28. Thereafter, the working cycle of inexsufflator 10 isgenerally as described previously. In terms of this embodiment ofinexsufflator 10, intrapulmonary pressure returns to atmosphericpressure during the pause period between the termination of exsufflationand the initiation of the next insufflation.

In a second embodiment, source 16 of positive fluid pressure is astandard volume-cycled or time-cycled pressure-limited ventilator, forexample, an LP-10 Volume Ventilator (Nellcor Puritan Bennet Inc.Pleasanton, CA) or an LTV-1000 Ventilator (Pulmonetic Systems, Colton,CA). A volume-cycled ventilator is a ventilator in which the amount ofair delivered to the patient by the ventilator with each inspiration isa predefined volume of air. In other words, the ventilator terminatesairflow and ends the phase of inspiration when a predefined volume ofair has entered the patient. This is to be contrasted with a time-cycledventilator, in which the amount of air delivered to the patient by theventilator with each inspiration is of an a-priori undefined volume, andthe ventilator terminates airflow and ends the phase of inspiration whena predefined inspiratory time has been achieved. Similarly, standardinexsufflators, such as the CoughAssist Inexsufflator, terminatepositive pressure airflow and end the phase of insufflation when apredefined inspiratory time, but not volume, has been achieved.

In this second embodiment, prior to initiation of the working cycledescribed above, the user sets ventilation parameters for the ventilatorso as to achieve maximal insufflation with each delivered ventilatorbreath, by choosing an appropriate value for the tidal volume (if avolume cycled ventilator is being used) or for the peak inspiratorypressure (if a time-cycled pressure-limited ventilator is being used).Thereafter, the working cycle of inexsufflator 10 is generally asdescribed previously. As standard volume-cycled or time-cycledventilators may not be capable of maintaining positive pressure withinthe patient's airway during expiration, in terms of this embodiment ofinexsufflator 10 intrapulmonary pressure may return to atmosphericpressure during the pause period between the termination of exsufflationand the initiation of the next insufflation by the ventilator.

In a third embodiment of the present invention, source 16 of positivefluid pressure is a ventilator that is capable of generating positivepressure within the patient's airway during expiration, such as a BiPAPSynchrony Ventilator (Respironics Inc. Pittsburgh, Pa.). In thisembodiment, prior to initiating the working cycle as described above,the user sets ventilation parameters for the BiPAP ventilator so as toachieve maximal insufflation with each delivered ventilator breath (bychoosing an appropriate value for the inspiratory positive airwaypressure—“IPAP”) and so as to achieve a desired expiratory positiveairway pressure between inexsufflation cycles, i.e. during theventilator's expiratory cycle. Thereafter, the working cycle ofinexsufflator 10 is generally as described previously. During the pauseperiod between the termination of exsufflation and the initiation of thenext insufflation by the ventilator, intrapulmonary pressure may bemaintained at a supra-atmospheric PEEP level by the ventilator.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of the features describedhereinabove as well as modifications and variations thereof which wouldoccur to a person of skill in the art upon reading the foregoingdescription and which are not in the prior art.

1. An inexsufflator for cough simulation to remove broncho-pulmonarysecretions of a patient comprising: a patient interface unit configuredto permit fluid flow therethrough at a flow rate of at least 160liters/minute; a source of negative fluid pressure configured togenerate the flow rate of at least 160 liters/minute; and a valve incommunication with the patient interface unit, a port of the source ofnegative fluid pressure, and a port of a volume-cycled ventilator, saidvalve configured to selectively connect said patient interface unit withone of said port of said volume-cycled ventilator and said port of saidsource of negative fluid pressure and to selectively seal fluid flowbetween said patient interface unit and one of said port of saidvolume-cycled ventilator and said port of said source of negative fluidpressure, wherein actuation of the valve from a first position to asecond position at or near lung capacity of the patient initiatesexsufflation of the lung to simulate a cough.
 2. The inexsufflatoraccording to claim 1, wherein said patient interface unit comprises oneof the following: a facemask, a tracheostomy tube, or an endotrachealventilation tube.
 3. The inexsufflator according to claim 1, whereinsaid valve comprises a manually actuated valve.
 4. The inexsufflatoraccording to claim 1 further comprising, a pressure sensor configured tosense one of a negative fluid pressure or a positive fluid pressure. 5.The inexsufflator according to claim 1, wherein said source of negativefluid pressure comprises a medical suction unit.
 6. An inexsufflator forcough simulation to remove broncho-pulmonary secretions of a patientcomprising: a patient interface unit configured to permit fluid flowtherethrough at a flow rate of at least 160 liters/minute; a source ofnegative fluid pressure configured to generate the flow rate of at least160 liters/minute; and a valve in communication with the patientinterface unit, a port of the source of negative fluid pressure, and aport of a ventilator capable of generating a positive end expiratorypressure, said valve configured to selectively connect said patientinterface unit with one of said port of said ventilator and said port ofsaid source of negative fluid pressure and to selectively seal fluidflow between said patient interface unit and one of said port of saidventilator and said port of said source of negative fluid pressure,wherein actuation of the valve from a first position to a secondposition at or near lung capacity of the patient initiates exsufflationof the lung to simulate a cough.
 7. The inexsufflator according to claim6, wherein said patient interface unit comprises one of the following: afacemask, a tracheostomy tube, or an endotracheal ventilation tube. 8.The inexsufflator according to claim 6, wherein said valve comprises amanually actuated valve.
 9. The inexsufflator according to claim 6further comprising, a pressure sensor configured to sense one of anegative fluid pressure or a positive fluid pressure.
 10. Theinexsufflator according to claim 6, wherein said source of negativefluid pressure comprises a medical suction unit.